A file server is a type of storage server which operates on behalf of one or more clients to store and manage shared files in a set of mass storage devices, such as magnetic or optical storage based disks. The mass storage devices are typically organized as one or more groups of Redundant Array of Independent (or Inexpensive) Disks (RAID). One configuration in which file servers can be used is a network attached storage (NAS) configuration. In a NAS configuration, a file server can be implemented in the form of an appliance, called a filer, that attaches to a network, such as a local area network (LAN) or a corporate intranet. An example of such an appliance is any of the NetApp Filer products made by Network Appliance, Inc. in Sunnyvale, Calif.
A filer may be connected to a network, and may serve as a storage device for several users, or clients, of the network. For example, the filer may store user directories and files for a corporate or other network, such as a LAN or a wide area network (WAN). Users of the network can be assigned an individual directory in which they can store personal files. A user's directory can then be accessed from computers connected to the network.
A system administrator can maintain the filer, ensuring that the filer continues to have adequate free space, that certain users are not monopolizing storage on the filer, etc. A Multi-Appliance Management Application (MMA) can be used to monitor the storage on the filer. An example of such an MMA is the Data Fabric Monitor (DFM) products made by Network Appliance, Inc. in Sunnyvale, Calif. The MMA may provide a Graphical User Interface (GUI) that allows the administrator to more easily observe the condition of the filer.
The MMA needs to collect information about files stored on the filer to report back to the administrator. This typically involves a scan, also referred to as a “file walk” of storage on the filer. During the file walk, the MMA can determine characteristics of files stored on the filer, as well as a basic structure, or directory tree, of the directories stored thereon. These results can be accumulated, sorted, and stored in a database, where the administrator can later access them. The MMA may also summarize the results of the file walk so they are more easily readable and understood by the administrator.
On a large system, the file walk can be a very intensive process. Additionally, the results of a typical file walk can themselves be very large and difficult to parse. An MMA typically has many tasks to perform, and generally should be available for the administrator. What is needed is a way to reduce the load on an MMA while still maintaining and monitoring attached appliances.